• Tofu Ninja (15/15) Jun 24 2015 Is this intended or is it a bug?
• Adam D. Ruppe (25/26) Jun 24 2015 Intended, the mixin template works on the basis of names. This
• SimonN (28/32) Jun 30 2015 I would like to to this with constructors instead of normal

"Tofu Ninja" <emmons0 purdue.edu> writes:

Is this intended or is it a bug?

void main(string[] args)
{
	Test a;
	a.foo(5); // Fails to compile
}

struct Test
{
	mixin testMix;
	void foo(string y){}
}

mixin template testMix()
{
	void foo(int x){}
}

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Thursday, 25 June 2015 at 03:49:04 UTC, Tofu Ninja wrote:
 Is this intended or is it a bug?

Intended, the mixin template works on the basis of names. This 
means that you can override methods from the mixin by writing a 
member with the same name - very useful thing - but also means no 
overloading happens without an extra step.

The extra step is easy though: alias the name in:

  void main(string[] args)
  {
  	Test a;
  	a.foo(5); // works!
	a.foo("4qsda");
  }

  struct Test
  {
  	mixin testMix tm; // give it a name to reference later
  	void foo(string y){}
	alias tm.foo foo; // alias the mixin thing too
  }

  mixin template testMix()
  {
  	void foo(int x){}
  }



By adding that explicit alias, it tells the compiler that yes, 
you do want it added to the set, not completely overridden by 
your replacement method.

"SimonN" <eiderdaus gmail.com> writes:

 On Thursday, 25 June 2015 at 03:49:04 UTC, Tofu Ninja wrote:
 Is this intended or is it a bug?


On Thursday, 25 June 2015 at 03:53:58 UTC, Adam D. Ruppe wrote:
 Intended, the mixin template works on the basis of names. This 
 The extra step is easy though: alias the name in:

I would like to to this with constructors instead of normal 
methods. I have tried to mix in a constructor as follows:



     import std.stdio;

     mixin template MyConstructor() {
         this(int x, float y) { writefln("%d, %f", x, y); }
     }

     class Base {
         mixin MyConstructor my_ctor;
         this(string s) { writefln(s); }
         alias my_ctor this;
     }

     void main()
     {
         Base b = new Base(3, 4.5);
     }

$ ./mixinctor.d
./mixinctor.d(17): Error: constructor mixinctor.Base.this (string 
s) is not callable using argument types (int, double)
Failed: ["dmd", "-v", "-o-", "./mixinctor.d", "-I."]

Doing it with
     alias this = my_ctor;
errors out too, and demands me to use alias my_ctor this; as in 
the original code.

Can I get this to work at all? Or does alias this (for multiple 
subtyping) fundamentally clash here with alias my_ctor this?

-- Simon